﻿namespace HelperLibrary;

public class CacheHelper
{
    private static readonly IMemoryCache _cache = new MemoryCache(new MemoryCacheOptions());
    

    #region 缓存

    /// <summary>
    /// 验证缓存项是否存在
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <returns></returns>
    public static bool Exists(string key)
    {
        if (key == null)
            throw new ArgumentNullException(nameof(key));
        return _cache.TryGetValue(key, out _);
    }

    /// <summary>
    /// 添加缓存
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <param name="value">缓存Value</param>
    /// <param name="expiresSliding">滑动过期时长（如果在过期时间内有操作，则以当前时间点延长过期时间）</param>
    /// <param name="expiressAbsoulte">绝对过期时长</param>
    /// <returns></returns>
    public static bool Set(string key, object value, TimeSpan expiresSliding, TimeSpan expiressAbsoulte)
    {
        if (key == null)
            throw new ArgumentNullException(nameof(key));
        if (value == null)
            throw new ArgumentNullException(nameof(value));

        _cache.Set(key, value,
            new MemoryCacheEntryOptions().SetSlidingExpiration(expiresSliding)
                .SetAbsoluteExpiration(expiressAbsoulte));
        return Exists(key);
    }

    /// <summary>
    /// 添加缓存
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <param name="value">缓存Value</param>
    /// <param name="expiresIn">缓存时长</param>
    /// <param name="isSliding">是否滑动过期（如果在过期时间内有操作，则以当前时间点延长过期时间）</param>
    /// <returns></returns>
    public static bool Set(string key, object value, TimeSpan expiresIn, bool isSliding = false)
    {
        if (key == null)
            throw new ArgumentNullException(nameof(key));
        if (value == null)
            throw new ArgumentNullException(nameof(value));

        _cache.Set(key, value,
            isSliding
                ? new MemoryCacheEntryOptions().SetSlidingExpiration(expiresIn)
                : new MemoryCacheEntryOptions().SetAbsoluteExpiration(expiresIn));

        return Exists(key);
    }

    /// <summary>
    /// 删除缓存
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <returns></returns>
    public static void Remove(string key)
    {
        if (key == null)
            throw new ArgumentNullException(nameof(key));

        _cache.Remove(key);
    }

    /// <summary>
    /// 批量删除缓存
    /// </summary>
    /// <returns></returns>
    public static void RemoveAll(IEnumerable<string> keys)
    {
        if (keys == null)
            throw new ArgumentNullException(nameof(keys));
        foreach(var item in keys.ToList())
        {
            _cache.Remove(item);
        }
    }

    /// <summary>
    /// 获取缓存
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <returns></returns>
    public static T Get<T>(string key) where T : class
    {
        if (key == null)
            return null;

        return _cache.Get(key) as T;
    }

    /// <summary>
    /// 获取缓存
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <returns></returns>
    public static object Get(string key)
    {
        if (key == null)
            return null;

        return _cache.Get(key);
    }

    /// <summary>
    /// 获取缓存集合
    /// </summary>
    /// <param name="keys">缓存Key集合</param>
    /// <returns></returns>
    public static IDictionary<string, object> GetAll(IEnumerable<string> keys)
    {
        if (keys == null)
            throw new ArgumentNullException(nameof(keys));

        var dict = new Dictionary<string, object>();
        foreach (var item in keys)
        {
            dict.Add(item, _cache.Get(item));
        }
        return dict;
    }

    /// <summary>
    /// 删除所有缓存
    /// </summary>
    public static void RemoveCacheAll()
    {
        var l = GetCacheKeys();
        foreach (var s in l)
        {
            Remove(s);
        }
    }

    /// <summary>
    /// 删除匹配到的缓存
    /// </summary>
    /// <param name="pattern"></param>
    /// <returns></returns>
    public static void RemoveCacheRegex(string pattern)
    {
        IList<string> l = SearchCacheRegex(pattern);
        foreach (var s in l)
        {
            Remove(s);
        }
    }

    /// <summary>
    /// 搜索 匹配到的缓存
    /// </summary>
    /// <param name="pattern"></param>
    /// <returns></returns>
    public static IList<string> SearchCacheRegex(string pattern)
    {
        var cacheKeys = GetCacheKeys();
        var l = cacheKeys.Where(k => Regex.IsMatch(k, pattern)).ToList();
        return l.AsReadOnly();
    }

    /// <summary>
    /// 获取所有缓存键
    /// </summary>
    /// <returns></returns>
    public static List<string> GetCacheKeys()
    {
        const BindingFlags flags = BindingFlags.Instance | BindingFlags.NonPublic;
        var entries = _cache.GetType().GetField("_entries", flags).GetValue(_cache);
        var cacheItems = entries as IDictionary;
        var keys = new List<string>();
        if (cacheItems == null) return keys;
        foreach (DictionaryEntry cacheItem in cacheItems)
        {
            keys.Add(cacheItem.Key.ToString());
        }
        return keys;
    }

    /// <summary>
    /// 添加缓存（如果在过期时间内有操作，则以当前时间点延长过期时间）
    /// </summary>
    /// <param name="key">缓存Key</param>
    /// <param name="value">缓存Value</param>
    /// <param name="expiresIn">缓存时长</param>
    /// <returns></returns>
    public static bool SetCache(string key, object value, TimeSpan expiresIn)
    {
        if (key == null)
            throw new ArgumentNullException(nameof(key));
        if (value == null)
            throw new ArgumentNullException(nameof(value));

        MemoryCacheEntryOptions cacheEntityOps = new MemoryCacheEntryOptions();
        cacheEntityOps.SetSlidingExpiration(expiresIn);
        
        cacheEntityOps.RegisterPostEvictionCallback((key, value, reason, state) => {
            //Console.WriteLine($"回调函数输出【键:{key},值:{value},被清除的原因:{reason}】");
        });

        _cache.Set(key, value, cacheEntityOps);
        return Exists(key);
    }

    #endregion
}
